1 files changed, 53 insertions, 16 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1d041aff4d48..e0ace3d9382c 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -44,6 +44,7 @@
  */
 static struct cpufreq_driver *cpufreq_driver;
 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
+static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data_fallback);
 static DEFINE_RWLOCK(cpufreq_driver_lock);
 static DEFINE_MUTEX(cpufreq_governor_lock);
 
@@ -946,6 +947,20 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
 }
 #endif
 
+static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
+{
+        struct cpufreq_policy *policy;
+        unsigned long flags;
+
+        write_lock_irqsave(&cpufreq_driver_lock, flags);
+
+        policy = per_cpu(cpufreq_cpu_data_fallback, cpu);
+
+        write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+        return policy;
+}
+
 static struct cpufreq_policy *cpufreq_policy_alloc(void)
 {
         struct cpufreq_policy *policy;
@@ -1023,7 +1038,12 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
                 goto module_out;
         }
 
-        policy = cpufreq_policy_alloc();
+        if (frozen)
+                /* Restore the saved policy when doing light-weight init */
+                policy = cpufreq_policy_restore(cpu);
+        else
+                policy = cpufreq_policy_alloc();
+
         if (!policy)
                 goto nomem_out;
 
@@ -1204,6 +1224,10 @@ static int __cpufreq_remove_dev(struct device *dev,
         data = per_cpu(cpufreq_cpu_data, cpu);
         per_cpu(cpufreq_cpu_data, cpu) = NULL;
 
+        /* Save the policy somewhere when doing a light-weight tear-down */
+        if (frozen)
+                per_cpu(cpufreq_cpu_data_fallback, cpu) = data;
+
         write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
         if (!data) {
@@ -1249,27 +1273,40 @@ static int __cpufreq_remove_dev(struct device *dev,
                 if (cpufreq_driver->target)
                         __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT);
 
-                lock_policy_rwsem_read(cpu);
-                kobj = &data->kobj;
-                cmp = &data->kobj_unregister;
-                unlock_policy_rwsem_read(cpu);
-                kobject_put(kobj);
+                if (!frozen) {
+                        lock_policy_rwsem_read(cpu);
+                        kobj = &data->kobj;
+                        cmp = &data->kobj_unregister;
+                        unlock_policy_rwsem_read(cpu);
+                        kobject_put(kobj);
+
+                        /*
+                         * We need to make sure that the underlying kobj is
+                         * actually not referenced anymore by anybody before we
+                         * proceed with unloading.
+                         */
+                        pr_debug("waiting for dropping of refcount\n");
+                        wait_for_completion(cmp);
+                        pr_debug("wait complete\n");
+                }
 
-                /* we need to make sure that the underlying kobj is actually
-                 * not referenced anymore by anybody before we proceed with
-                 * unloading.
+                /*
+                 * Perform the ->exit() even during light-weight tear-down,
+                 * since this is a core component, and is essential for the
+                 * subsequent light-weight ->init() to succeed.
                  */
-                pr_debug("waiting for dropping of refcount\n");
-                wait_for_completion(cmp);
-                pr_debug("wait complete\n");
-
                 if (cpufreq_driver->exit)
                         cpufreq_driver->exit(data);
 
-                cpufreq_policy_free(data);
+                if (!frozen)
+                        cpufreq_policy_free(data);
         } else {
-                pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
-                cpufreq_cpu_put(data);
+
+                if (!frozen) {
+                        pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
+                        cpufreq_cpu_put(data);
+                }
+
                 if (cpufreq_driver->target) {
                         __cpufreq_governor(data, CPUFREQ_GOV_START);
                         __cpufreq_governor(data, CPUFREQ_GOV_LIMITS);